Climate Change Timeline

EDITOR'S NOTE:
This article was originally published by the American Institute of Physics and {C}Spencer Weart as Timeline of Milestones. The original version contains detailed references and links to additional information on the history of climate change science.

1800-1870

Level of {C}carbon dioxide gas (CO2) in the atmosphere, as later measured in ancient ice, is about 290 ppm (parts per million). Mean global temperature (1850-1870) is about 13.6°C.

Creation of US National Oceanic and Atmospheric Administration, the world's leading funder of climate research.

Aerosols from human activity are shown to be increasing swiftly. Bryson claims they counteract global warming and may bring serious cooling.

1971

SMIC conference of leading scientists reports a danger of rapid and serious global change caused by humans, calls for an organized research effort.

Mariner 9 spacecraft finds a great dust storm warming the atmosphere of Mars, plus indications of a radically different climate in the past .

1972

Ice cores and other evidence show big climate shifts in the past between relatively stable modes in the space of a thousand years or so, especially around 11,000 years ago.

1973

Oil embargo and price rise bring first "energy crisis".

1974

Serious droughts and other unusual weather since 1972 increase scientific and public concern about climate change, with cooling from aerosols suspected to be as likely as warming; journalists talk of ice age.

1975

Concern about environmental effects of airplanes leads to investigations of trace gases in the stratosphere and discovery of danger to ozone layer.

Manabe and collaborators produce complex but plausible computer models which show a temperature rise of several degrees for doubled CO2.

1976

Studies show that CFCs (1975) and also methane and ozone (1976) can make a serious contribution to the greenhouse effect.

Deep-sea cores show a dominating influence from 100,000-year Milankovitch orbital changes, emphasizing the role of feedbacks.

Deforestation and other ecosystem changes are recognized as major factors in the future of the climate.

Eddy shows that there were prolonged periods without sunspots in past centuries, corresponding to cold periods.

1977

Scientific opinion tends to converge on global warming, not cooling, as the chief climate risk in next century.

1978

Attempts to coordinate climate research in US end with an inadequate National Climate Program Act, accompanied by rapid but temporary growth in funding.